Translation notes:
Thanks to Kaijyuu M for taking a look at my translation and offering corrections; any mistakes left are completely my responsibility! Several things were tricky to wrestle with:
1. Obieteru - The kanji used is like the kanji for obi (tie). But as a verb form, that becomes obiru (tie, wear, carry, be burdened with, be stained with). Obieteru sounds as though it came from obieru (be afraid of). But since I'd prefer to get the meaning from the kanji rather than the pronunciation, I took it as the other half of a pair, like kesu/kieru or miru/mieru. After much wrestling, I decided "tangled up in" seemed like it best fit the tone of the song.
2. The parallel stanzas (nanika ni obieteru... and namida ga koboreteru...) seemed to have some inversions built into both of them. (At least, the third line of each seemed to start a new thought and the second line seemed to need part of the first line as a verb.) So I did some section-shuffling there.
3. Rikutsu ga motto hoshikunaru: I think that means something like "I'm starting to want something about this relationship to make more sense," but that was a lot of extrapolating, so I left the translation more vague.
4. Kieru kage ni mabushisugita hibi wo utsushiteru -- It could be argued that the unspecified topic/caster of the shadow is "I", "you", or something about the relationship. I had to flip a coin based on what I thought the rest of the song felt like, and I can't really explain why I thought it ought to be the singer's "you" other than "it felt like an equivalent inversion" (casting a "shadow" of light, things vanishing into the brilliance rather than the darkness, and someone else's actions being what the singer is trying not to be nostalgic about.) If you want to read it another way, feel free...